Assigning fixed IP to generated VDI desktops

[Miloslav Hůla]

Hi,

we are running VMware platform with virtual desktops (VDI) with Windows 
7/8.1/10. We are dealing with fixed address asignment by ISC DHCP Server 
(4.3.1-6+deb8u2 Debian Jessie) to stations generated with random MAC 
addresses.

The basic steps are following:

1) prepare a golden image (the source Windows machine)
2) generate the pool of windows desktops based on the golden

Let's say, we are creating a pool of 50 office desktops. We are telling 
to VMware: "Create office-01 to office-50 from golden". The process for 
every new station is:

a) Take golden with known MAC1 and hostname 'golden'.
b) Clone golden. The result is a windows machine with new random MAC2, 
but hostname is still 'golden'.
c) Boot up new machine and run customization scripts. The result is the 
hostname is changed to 'office-01'.
d) Reboot machine (and run some other scripts)
e) Power off the machine. It's done.

We are assigning IP addresses by making classes based on host-name 
option matching.

The problem is, that in step b) we have machine with hostname 'golden' 
and MAC2. So, DHCP server creates a lease for it from dynamic range. 
Then machine reboots and have hostname 'office-01' and still MAC2 in 
steps c) and d). Now we need to assign fixed IP by hostname, but there 
is already lease for it and DHCP server offers this one.

My question is, is there some kind of prefences we could do? I read in 
manual that priorities are host, class, pool, subnet, shared-network.

I read in manual about "host-identifier option option-name option-data" 
but it is for DHCPv6. Or it is not? Because I found some posts in this 
list pointing to DHCPv4 too.

And another questions, possibly not so related. We are running separated 
DHCP server for VDI. And we have a two next DHCP servers in fail-over 
mode for the rest of the network. The whole network has about 130 
subnets and 100 VLANs. We would like to merge VDI DHCP server with the 
two others. The question is, the host-name matching must work only for 
VDI VLAN. If I understand manual correctly, class declarations are 
global. Could it be done by subclasses?

And the last question. How DHCP server handles requests from DHCP relay? 
In log we can see:

- via eth0
- via eth1
- via 10.70.0.1

I guess, that server fetches current eth0 or eth1 IP addresses and match 
the subnets according to. Is it the same for the relay? Subnet is 
matched by the relay IP address?


Thank you very much and sorry for such long post. We have done some 
"working" configuration but every body is affraid to make some change, 
because no one of us really knows how it works :)

Kind regards, Milo